RNA activation(RNAa)is a phenomenon of up-regulation of gene expression by small activating RNAs(saRNAs).Using the progesterone receptor(PR)gene as a model,we established a big panel of effective saRNAs and assessed the possible involvement of the two strands in RNA activation.All active saRNAs were found to have their antisense strand effectively incorporated into Ago2,whereas such consistency did not occur for the sense strand.